It is not hard to understand the continuing fascination with the crimes of Jack the Ripper 130 years on. Besides the shoal of books, there is even a new museum to exploit his ghastliness. The ferocious, psychopathic murders of prostitutes in the grim backstreets of the Victorian East End make a suitably gothic story, even without the theatrical mist that generally swirls around the case and its shadowy perpetrator. Best of all, Jack was never caught by the incompetent London police of the time, so it will forever be open season in identifying him. The list of suspects, from the likely to the ludicrous (the Duke of Clarence and Walter Sickert rub up against sundry failed barristers and doctors, immigrants and ne’er-do-wells) can never be closed.

What is more surprising is the vigour and venom with which individual Ripperologists championing their man belabour their rivals as idiots and dupes. A few years ago the American author Patricia Cornwell was buying up Sickerts and ripping some to shreds to prove her theory that the artist was to